Combustion equipment for a gas turbine engine



Aug. 16, 1966 F. FREEMAN ETAL Filed Jan. 20, 1964 2 Sheets-Sheet 1 6, 1966 F. FREEMAN ETAL 3,266,250

COMBUSTION EQUIPMENT FOR A GAS TURBINE ENGINE Filed Jan. 20, 1964 2 Sheets-Sheet f1 United States Patent 3,266,250 COMBUSTION EQUIPMENT FOR A GAS TURBINE ENGINE Frederick Freeman, Derby, and Herbert Frank Smith, Allenton, Derby, England, assignors to Rolls-Royce Limited, Derby, England, a company of Great Britain Filed Jan. 20, 1964, Ser. No. 338,966 Claims priority, application Great Britain, Jan. 31, 1963, 4,127/ 63 3 Claims. (Cl. 6039.36)

This invention concerns annular combustion equipment for a gas turbine engine.

According to the present invention there is provided annular combustion equipment for a gas turbine engine comprising an annular inlet passage which is adapted to receive air flowing in a radially outward direction, an annular combustion chamber within which there its a combustion zone, a plurality of angularly spaced apart dilution air chutes which extend into the inlet passage and which communicate with the combustion chamber downstream of the combustion zone, the arrangement being such that one portion of the air supplied to the inlet passage passes via the chutes and into the combustion chamber so as to dilute the combustion gases, while another portion of the air supplied to the inlet passage passes between said chutes and is supplied to the combustion zone so as to support combustion thereat, and an annular outlet passage which is adapted to receive the diluted combustion gases and to discharge them from the combustion equipment in a radially inward direction.

Preferably each of the said chutes passes through the wall of the combustion chamber and extends a substantial distance into the combustion chamber.

The Wall of each chute may be provided at its downstream end with a plurality of holes through which dilution air may enter the combustion chamber.

Means are preferably provided for dividing the said other portion of air into two parts one of which forms a primary air supply to the combustion chamber and the other of which forms a secondary air supply therefor.

The combustion chamber is preferably substantially elliptical in cross section, the inlet passage extends around the greater part of the wall of the combustion chamber, and the outlet passage is disposed between the combustion chamber and the inlet end of the inlet passage.

Preferably the maximum axial length of the combustion equipment is less than half the maximum diameter thereof.

Means are preferably provided for directing a further portion of the air supplied to the inlet passage past the wall of the outlet passage so as to cool the latter.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIGURE 1 is an elevation, partly in section, of a gas turbine engine provided with combustion equipment according to the present invention, and

FIGURE 2 is a broken away section taken on the line 2-2 of FIGURE 1.

Referring to the drawings, a gas turbine vertical lift engine for an aircraft comprises in flow series an air intake 11, a centrifugal compressor 12 having rotor blades 13, annular combustion equipment 14, an inward radial flow turbine 15 having rotor blades 16, and a short curved exhaust duct 17 leading to a nozzle 18.

The compressor 12 and turbine 15, which are mounted back to back on a common shaft 20, are drivingly coupled together by a toothed coupling 21 such as that sold under the registered trademark CUR-VIC.

The shaft 20 is rotatably mounted, by means of a front bearing 22, and a rear bearing 23, on a shaft 24,

3,266,250 Patented August 16, 1966 the shaft 20 being spaced for the shaft 24 by a space 25. Within the shaft 24 is mounted fuel supply control equipment 26 which controls the supply of fuel to the combustion equipment 14. An oil reservoir 27 is disposed immediately above the front bearing 22, and oil may flow from the reservoir 27 and then through the space 25 to the rear bearing 23.

Oil may be supplied to the reservoir 27 (e.g. in the form of a single shot of oil), and fuel may be supplied to the fuel supply control equipment 26, by means of pipes (not shown) which pass through a hollow struct extending across the air intake 11.

The combustion equipment 14 comprises an annular inlet passage 31 which is adapted to receive air flowing in a radially outward direction from the compressor 12.

Mounted within and adjacent the inlet end of the inlet passage 31 are diffuser vanes 32. The inlet passage 31, on the downstream side of the diffuser vanes 32, is bent through a right angle so as to have an annular axially extending portion 33 in which are mounted flow straightening vanes 34.

The upstream ends of a plurality of angularly spaced apart dilution air chutes 35 extend into the portion 33 of the inlet passage 31, immediately downstream of the vanes 34. Each of the chutes 35 extends through an aperture 36 in the wall 37 of an annular combustion chamber 40 which is substantially elliptical in crosssection. Each chute 35 extends a substantial distance into the combustion chamber 40, and the wall of each chute 35 is provided at its downstream end with a plurality of holes 41.

About 60% of the compressed air in the inlet passage 31 passes via the chutes 35 and holes 41 into the combustion chamber 40 downstream of the combustion zone 42 therein. This portion of the air is used to dilute the combustion gases so as to reduce their temperature to a valve acceptable to the turbine 15. Most of the remaining 40% of the compressed air passes between the chutes 35 and through a radially inwardly directed portion 43 of the inlet passage 31.

A portion of the compressed air from the portion 43 passes through apertures in a plate 44 forming part of the wall 37, this portion constituting primary combustion air for supply to burners 45 in the combustion zone 42.

The remainder of the compressed air from the portion 43 passes through a portion 46 of the inlet passage 31 and enters the combustion chamber 40, as secondary air, through apertures 47 in the wall 37. This secondary air completes the combustion in the combustion zone 42 and stabilises the primary combustion gas flow recirculation.

The combustion equipment 14 has an annular outlet passage 50 which receives the diluted combustion gases from the combustion chamber 40 and discharges them radially inwardly to the turbine 15. The outlet passage 50 is disposed between the combustion chamber 40 and the inlet end of the inlet passage 31. Turbine nozzle guide vanes 51 are mounted in the outlet passage 50.

As will be seen from FIGURE 1, the inlet passage 31 extends around and so cools the greater part of the wall 37 of the combustion chamber 40.

A small proportion of the compressed air in the inlet passage 31 is directed through a passage 52 and past the wall of the outlet passage 50* so as to cool the latter. This air then passes between the compressor 12 and turbine 15, through the coupling 21, and thence inwardly of the turbine 15 so as to pass int-o the turbine exhaust gases.

As will be seen for FIGURE 1, the maximum axial length of the combustion equipment 14 is less than half (e.g. is about one-third) of its maximum diameter.

Similarly, the maximum axial length of the engine 10 is substantially less (cg. is about one-third less) than its maximum diameter. This axial compactness of the combustion equipment 14 and of the whole engine 10 is an important feature since it permits the engine 10 to be installed in the fuselage or wing of an aircraft where there may be limited room for the axial extent of an engine.

We claim:

1. Annular combustion equipment for a gas turbine engine comprising an annular combustion chamber having a substantially elliptical cross-section within which there is a combustion zone, an annular inlet passage which receives air flowing in a radially outward direction and which extends around the greater part of the wall of the combustion chamber, a plurality of angularly spacedapart dilution air chutes which extend into the inlet passage and which communicate with the combustion chamber downstream of the combustion zone, means ensuring that one portion of the air supplied to the inlet passage passes via the chutes and into the combustion chamber so as to dilute the combustion gases, while another portion of the air supplied to the inlet passage passes between said chutes and is supplied to the combustion zone so as to support combustion thereat, means for dividing the said other portion of air into two parts one of which forms a primary air supply to the combustion chamber and the other of which forms a secondary air supply therefor, and an annular outlet passage which is disposed between the combustion chamber and the inlet end of the inlet passage and which is adapted to receive the diluted combustion gases and to discharge them from the combustion equipment in a radially inward direction.

2. Annular combustion equipment as claimed in claim 1 wherein the maximum axial length of the combustion equipment is less than half the maximum diameter thereof.

3. Annular combustion equipment as claimed in claim 1 in which the inlet passage is provided with flow straightening vanes.

References Cited by the Examiner UNITED STATES PATENTS 2,709,893 6/1955 Birmann. 2,826,039 3/1958 Ashwood 6039.65

2,856,755 10/1958 Szydlo-wski 6035.6

MARK NEWMAN, Primary Examiner.

RALPH D. BLAKESLEE, Examiner. 

1. ANNULAR COMBUSTION EQUIPMENT FOR A GAS TURBINE ENGINE COMPRISING AN ANNULAR COMBUSTION CHAMBER HAVING A SUBSTANTIALLY ELLIPTICAL CROSS-SECTION WITHIN WHICH THERE IS A COMBUSTION ZONE, AN ANNULAR INLET PASSAGE WHICH RECEIVES AIR FLOWING IN A RADIALLY OUTWARD DIRECTION AND WHICH EXTENDS AROUND THE GREATER PART OF THE WALL OF THE COMBUSTION CHAMBER, A PLURALITY OF ANGULARLY SPACEDAPART DILUTION AIR CHUTES WHICH EXTEND INTO THE INLET PASSAGE AND WHICH COMMUNICATE WITH THE COMBUSTION CHAMBER DOWNSTREAM OF THE COMBUSTION ZONE, MEANS ENSURING THAT ONE PORTION OF THE AIR SUPPLIED TO THE INLET PASSAGE PASSES VIA THE CHUTES AND INTO THE COMBUSTION CHAMBER SO AS TO DILUTE THE COMBUSTION GASES, WHILE ANOTHER PORTION OF 